ebay, ebay, ebay
- all the accessory sites in one place FTW! Definitely the best prices are there. When i sold cellies, i used cases just so i would sell more accessories - and it works 
in terms of brand, i like Moto bluetooth products, and Blue Ant too. I had one of those Aliph Jawbones, but it was so difficult to put on my ear that i don't use it anymore. In terms of chargers, OEM all the way ... after market chargers are cheap but they're also flimsy and don't work as well as the original equipment of the manufacturer of the phone. In terms of cases, it really depends on what's available for the phone i'm accessorizing.
oh and ladies, please ... if you love your phone, don't ever do this to it
your phone will never forgive you